Comparison of Mechanical Reinforcement Effects of Cellulose Nanofibers and Montmorillonite in Starch Composite

Recent advances in reinforced bioplastics for food packaging - A critical review

Recently, diversifying the material, method, and application in food packaging has been massively developed to find more environment-friendly materials. However, the mechanical and barrier properties of the bioplastics are major hurdles to expansion in commercial realization. The compositional variation with the inclusion of different fillers could resolve the lacking performance of the bioplastic. This review summarizes the various reinforcement fillers and their effect on bioplastic development. In this review, we first discussed the status of bioplastics and their definition, advantages, and limitations regarding their performance in the food packaging application. Further, the overview of different fillers and development methods has been discussed thoroughly. The application of reinforced bioplastic for food packaging and its effect on food quality and shelf life are highlighted. The environmental issues, health concerns, and future perspectives of the reinforced bioplastic are also discussed at the end of the manuscript. Adding different fillers into the bioplastic improves physical, mechanical, barrier, and active properties, which render the required protective functions to replace conventional plastic for food packaging applications. Various fillers, such as natural and chemically synthesized, could be incorporated into the bioplastic, and their overall properties improve significantly for the food packaging application.

From macro- to nano- scales: Effect of fibrillary celluloses from okara on performance of edible starch film

Starch/cellulose composite is one of the most promising systems since both matrix and reinforce agent have same chemical unite glucose, which results in an excellent compatibility. In this work, edible starch film was developed by compositing starch with diverse fibrillary celluloses (FCs) derived from okara, employing a confluence of chemical interactions and mechanical influences. Since diameter of the FCs can be easily controlled by processing methodologies, it is the first time to systematically investigate the effect of diameter of the FCs from macro to nano-scales on the performances of starch-based film. The fabricated macro- and nano-fibrillar celluloses and reinforced starch films were characterized by scanning electron microscope, optical microscopy, Fourier transform infrared spectroscopy, Rheometer and contact angle. Results showed that the FCs increased modulus (about 170 %) and tensile strength (about 180 %) significantly as expected since they are well-compatible and some chemical interactions. It was found that nano-fibrillary celluloses (CNFs) improve the toughness (about 20 %) of the starch film more efficiently, which improved the well-recognized weakness of starch-based materials. The nano-scale roughness on the surface of the starch film caused by different shrinkage ratios between starch and CNFs during drying reduced water sensitivity, which is another well-recognized weakness of starch film.

Effect of cellulose nanofiber-montmorillonite hybrid filler on the melt blending of thermoplastic starch composites

This study investigated the impact of cellulose nanofibers (CNFs) on montmorillonites (MMTs) exfoliation within thermoplastic starch (TPS) nanocomposites during the melt blending process. TPS nanocomposite films were manufactured using an internal mixer with a controlled ratio of CNFs and MMTs to evaluate the effect of individual and hybrid fillers on the material interactions and characteristics of the TPS composites. The incorporation of hybrid fillers resulted in notable enhancements in torque values and rheological properties, suggesting interactions between the starch, CNFs, and MMTs. The degree of MMT intercalation, obtained via X-ray diffraction analysis, decreased with the addition of CNFs, indicating that CNFs positively impacted MMT exfoliation. Scanning electron microscopy (SEM) images of cryo- and tensile-fractured samples highlighted the effectiveness of CNFs in facilitating MMT exfoliation and reinforcing interactions between the MMTs and TPS matrix. These interactions enhanced the tensile strength and Young's modulus by up to 95.8 % and 278.2 %, respectively, with a 1:1 weight ratio of CNFs to MMTs. Additionally, well-dispersed MMTs within the TPS matrix caused passivation and created tortuous paths, improving the water contact angle and decreasing the water vapor sorption. These synergistic effects of the hybrid filler, achieved through a melt blending process, indicate the potential use of TPS nanocomposites as an eco-friendly packaging material.

Optimizing the Functional Properties of Starch-Based Biodegradable Films

A definitive screening design was used in order to evaluate the effects of starch, glycerol and montmorillonite (MMT) concentrations, as well as the drying temperature, drying tray type and starch species, on packaging film's functional properties. Optimization showed that in order to obtain films with the minimum possible thickness, the maximum elongation at break, the maximum tensile strength, as well as reduced water vapor permeability and low opacity, a combination of factors should be used as follows: 5.5% wt starch concentration, 30% wt glycerol concentration on a dry starch basis, 10.5% wt MMT concentration on a dry starch basis, 45 °C drying temperature, chickpea as the starch species and plexiglass as the drying tray type. Based on these results, starch films were prepared, and fresh minced meat was stored in them for 3 days. It was shown that the incorporation of MMT at 10.5% wt on a dry starch basis in the packaging films led to a decreased mesophilic and psychrotrophic bacteria growth factor compared to commercial packaging. When assessed for their biodegradability, the starch films disintegrated after 10 days of thermophilic incubation under simulated composting conditions. Finally, to prove their handling capability during industrial production, the starch films were rewound in a paper cylinder using an industrial-scale rewinding machine.

Thermoplastic starch nanocomposites: sources, production and applications - a review

The development of materials based on thermoplastic starch (TPS) is an excellent alternative to replace or reduce the use of petroleum-derived polymers. The abundance, renewable origin, biodegradability, biocompatibility, and low cost of starch are among the advantages related to the application of TPS compared to other thermoplastic biopolymers. However, through the literature review, it was possible to observe the need to improve some properties, to allow TPS to replace commonly used polyolefins. The studies reviewed achieved these modifications were achieved by using plasticizers, adjusting processing conditions, and incorporating fillers. In this sense, the addition of nanofillers proved to be the main modification strategy due to the large number of available nanofillers and the low charge concentration required for such improvement. The improvement can be seen in thermal, mechanical, electrical, optical, magnetic, antimicrobial, barrier, biocompatibility, cytotoxicity, solubility, and swelling properties. These modification strategies, the reviewed studies described the development of a wide range of materials. These are products with great potential for targeting different applications. Thus, this review addresses a wide range of essential aspects in developing of this type of nanocomposite. Covering from starch sources, processing routes, characterization methods, the properties of the obtained nanocomposites, to the various applications. Therefore, this review will provide an overview for everyone interested in working with TPS nanocomposites. Through a comprehensive review of the subject, which in most studies is done in a way directed to a specific area of study.

Preparation and characterization of starch-based nanocomposites reinforced by graphene oxide self-assembled on the surface of silanecouplingagent modified cellulose nanocrystals

The dispersion of cellulose nanocrystal (CNC) in starch matrix limited its application. In this study, CNC modified by silanecouplingagent before graphene oxide (GO) self-assembled on the surface of modified CNC, then CNC-GO as a filler was used to prepare starch-based nanocomposite films (CS/CNC-GO). The structure of CNC-GO and CS/CNC-GO films and the properties of CS/CNC-GO films were studied by FT-IR, Raman, SEM, surface potential, UV-Vis, moisture absorption and tensile tests. The results showed that GO was successfully self-assembled on the surface of CNC modified by silanecouplingagent. CNC-GO was superior to CNC in reinforcing the strength of starch film, improving the transmittance of starch film and decreasing moisture rate of starch film. Tensile strength, elongation at break and transmittance of CS/CNC-GO film with 5 wt% CNC-GO reached maximum, which was 53.96 MPa, 3.72% and 38.76%, respectively. Moisture rate of CS/CNC-GO film with 3 wt% CNC-GO reached minimum that was 12.13%. These were assigned to the more uniform dispersion of CNC-GO in the starch matrix and the stronger interfacial interaction between starch and CNC-GO.

A Comprehensive Review on the Emerging Roles of Nanofillers and Plasticizers towards Sustainable Starch-Based Bioplastic Fabrication

Petroleum-based plastics are associated with environmental pollution problems owing to their non-biodegradable and toxic properties. In this context, renewable and biodegradable bioplastics possess great potential to replace petroleum-based plastics in mitigating these environmental issues. Fabrication of bioplastic films involves a delicate mixture of the film-forming agent, plasticizer and suitable solvent. The role of the plasticizer is to improve film flexibility, whereas the filler serves as a reinforcement medium. In recent years, much research attention has been shifted toward devising diverse methods for enhancing the performance of bioplastics, particularly in the utilization of environmentally benign nanoparticles to displace the conventional hazardous chemicals. Along this line, this paper presents the emergence of nanofillers and plasticizers utilized in bioplastic fabrication with a focus on starch-based bioplastics. This review paper not only highlights the influencing factors that affect the optical, mechanical and barrier properties of bioplastics, but also revolves around the proposed mechanism of starch-based bioplastic formation, which has rarely been reviewed in the current literature. To complete the review, prospects and challenges in bioplastic fabrication are also highlighted in order to align with the concept of the circular bioplastic economy and the United Nations’ Sustainable Development Goals.